Refrigerant evaporator

ABSTRACT

A refrigerant evaporator includes: a first heat exchange part in which refrigerant flows; a second heat exchange part in which the refrigerant flows; a first tank arranged below the first heat exchange part to distribute the refrigerant to the first heat exchange part; a second tank arranged below the second heat exchange part to collect the refrigerant flowing through the second heat exchange part; and a third tank joined to the first tank and the second tank to introduce the refrigerant collected by the second tank to the first tank. A clearance is defined among the first tank, the second tank, and the third tank. At least one of a joint portion between the first tank and the third tank and a joint portion between the second tank and the third tank defines a drainage passage to discharge water trapped in the clearance.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2015-38169 filed on Feb. 27, 2015 and Japanese Patent Application No. 2016-32052 filed on Feb. 23, 2016, the disclosures of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a refrigerant evaporator in which heat is exchanged between a fluid to be cooled and a refrigerant.

BACKGROUND ART

Patent Literature 1 describes a refrigerant evaporator. The refrigerant evaporator described in Patent Literature 1 includes a first heat exchange part and a second heat exchange part in which heat is exchanged with air that is a fluid to be cooled. The first heat exchange part and the second heat exchange part are arranged to oppose in a flowing direction of air. The first heat exchange part is divided into a first core part and a second core part in a direction perpendicular to the flowing direction of air. The second heat exchange part is also divided into a first core part and a second core part in a direction perpendicular to the flowing direction of air. The first core part of the first heat exchange part opposes the first core part of the second heat exchange part in the flowing direction of air. The second core part of the first heat exchange part opposes the second core part of the second heat exchange part in the flowing direction of air. The refrigerant evaporator described in Patent Literature 1 includes a pair of tanks disposed at the respective ends of the first heat exchange part in the vertical direction, and a pair of tanks disposed at the respective ends of the second heat exchange part in the vertical direction. Moreover, the refrigerant evaporator described in Patent Literature 1 includes a switch tank between the tank disposed below the first heat exchange part in the vertical direction and the tank disposed below the second heat exchange part in the vertical direction.

In the refrigerant evaporator described in Patent Literature 1, refrigerant flows from the tank above the second heat exchange part in the vertical direction to the first core part and the second core part of the second heat exchange part. The refrigerant flowing into the first core part of the second heat exchange part flows from the tank below the second heat exchange part in the vertical direction through the switch tank and the tank below the first heat exchange part in the vertical direction into the second core part of the first heat exchange part. The refrigerant flowing into the second core part of the second heat exchange part flows from the tank below the second heat exchange part in the vertical direction through the switch tank and the tank below the first heat exchange part in the vertical direction into the first core part of the first heat exchange part. The refrigerant flowing into the first core part of the first heat exchange part, and the refrigerant flowing into the second core part of the first heat exchange part are discharged through the tank above the first heat exchange part in the vertical direction.

PRIOR ART LITERATURES Patent Literature

-   Patent Literature 1:JP 2013-185723A

SUMMARY OF INVENTION

In the refrigerant evaporator described in Patent Literature 1, water is condescend on the external surfaces of the first heat exchange part and the second heat exchange part, due to the heat exchange between refrigerant and air, and the condensed water flows downward in the vertical direction. If a clearance is formed among the tank below the first heat exchange part in the vertical direction, the tank below the second heat exchange part in the vertical direction, and the switch tank, the condensed water may stay in the clearance. If the water freezes, the freezing causes a crack, because the volume of water is increased to damage each tank.

It is an object of the present disclosure to provide a refrigerant evaporator in which a crack caused by freezing is restricted.

According to an aspect of the present disclosure, a refrigerant evaporator in which heat is exchanged between a fluid to be cooled and a refrigerant includes: a first heat exchange part in which the refrigerant flows to exchange heat between the fluid to be cooled and the refrigerant; a second heat exchange part in which the refrigerant flows to exchange heat between the fluid to be cooled and the refrigerant, the second heat exchange part being arranged to oppose the first heat exchange part; a first tank arranged below the first heat exchange part to distribute the refrigerant to the first heat exchange part; a second tank arranged below the second heat exchange part to collect the refrigerant flowing through the second heat exchange part; and a third tank joined to the first tank and the second tank to introduce the refrigerant collected by the second tank to the first tank. A clearance is defined among the first tank, the second tank, and the third tank. At least one of a joint portion between the first tank and the third tank, and a joint portion between the second tank and the third tank defines a drainage passage to discharge water trapped in the clearance.

According to an aspect of the present disclosure, a refrigerant evaporator in which heat is exchanged between a fluid to be cooled and a refrigerant includes: a first heat exchange part in which the refrigerant flows to perform heat exchange between the fluid to be cooled and the refrigerant; a second heat exchange part in which the refrigerant flows to perform heat exchange between the fluid to be cooled and the refrigerant, the second heat exchange part being arranged to oppose the first heat exchange part; a first tank arranged below the first heat exchange part to distribute the refrigerant to the first heat exchange part; a second tank arranged below the second heat exchange part to collect the refrigerant flowing through the second heat exchange part; a connection part that connects the first tank and the second tank to each other; and a third tank joined to the first tank and the second tank to introduce the refrigerant collected by the second tank to the first tank. At least one opening is defined in the connection part. At least one of a joint portion between the first tank and the third tank and a joint portion between the second tank and the third tank defines a drainage passage located on a lower side of the opening of the connection part to discharge water passing through the opening.

When the condensed water generated on the external surfaces of the first heat exchange part and the second heat exchange part flows into the clearance defined among the first tank, the second tank and the third tank, the condensed water is discharged outside through the drainage passage. Therefore, since the condensed water hardly stays in the clearance among the first tank, the second tank and the third tank, a crack caused by a freeze of the condensed water can be restricted.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating a refrigerant evaporator according to a first embodiment.

FIG. 2 is an exploded perspective view illustrating the refrigerant evaporator of the first embodiment.

FIG. 3 is an exploded perspective view illustrating a windward distribution tank, a leeward collection tank, and a switch tank of the refrigerant evaporator of the first embodiment.

FIG. 4 is a schematic perspective view illustrating a flow of refrigerant in the refrigerant evaporator of the first embodiment.

FIG. 5 is a side view illustrating a structure of a drainage passage of the refrigerant evaporator of the first embodiment.

FIG. 6 is a side view illustrating a structure of a drainage passage of a refrigerant evaporator according to a first modification of the first embodiment.

FIG. 7 is a side view illustrating a structure of a drainage passage of a refrigerant evaporator according to a second modification of the first embodiment.

FIG. 8 is a side view illustrating a structure of a drainage passage of a refrigerant evaporator according to a third modification of the first embodiment.

FIG. 9 is a side view illustrating a structure of a drainage passage of a refrigerant evaporator according to a fourth modification of the first embodiment.

FIG. 10 is a side view illustrating a structure of a drainage passage of a refrigerant evaporator according to a fifth modification of the first embodiment.

FIG. 11 is a sectional view illustrating a windward distribution tank, a leeward collection tank, and a switch tank of a refrigerant evaporator according to a second embodiment.

DESCRIPTION OF EMBODIMENTS First embodiment

Hereafter, a refrigerant evaporator of a first embodiment of is described. The refrigerant evaporator 1 of this embodiment shown in FIG. 1 is used for a refrigeration cycle for an air-conditioner for a vehicle, which conditions air in the cabin. Specifically, the refrigerant evaporator 1 is a cooling heat exchanger for cooling air by absorbing heat from air to be sent to the cabin to evaporate the liquid phase refrigerant. The refrigeration cycle includes a compressor, a radiator, an expansion valve, which are not illustrated but well known, in addition to the refrigerant evaporator 1.

As shown in FIG. 1 and FIG. 2, the refrigerant evaporator 1 includes two evaporation parts 10 and 20 and a switch tank 30. The evaporation part 10 is arranged on the upstream side and the evaporation part 20 is arranged on the downstream side in an air flowing direction X. In this embodiment, the air flowing direction X is a direction perpendicular to a vertical direction Y1, Y2. Hereafter, the evaporation part 10 arranged upstream in the air flowing direction X is called as “the windward side evaporation part 10.” Moreover, the evaporation part 20 arranged downstream in the air flowing direction X is called as “the leeward side evaporation part 20.”

The windward side evaporation part 10 has a windward side collection tank 11, a windward side heat exchange part 12, and a windward side distribution tank 13. The windward side collection tank 11, the windward side heat exchange part 12, and the windward side distribution tank 13 are arranged in this order downward in the vertical direction Y1.

The windward side heat exchange part 12 has a rectangular parallelepiped shape. The windward side heat exchange part 12 is arranged so that the air flowing direction X corresponds to the thickness direction. The windward side distribution tank 13 is attached to a lower-side end surface 12 d of the windward side heat exchange part 12 in the vertical direction Y1. The windward side collection tank 11 is attached to an upper-side end surface 12 e of the windward side heat exchange part 12 in the vertical direction Y2. The windward side heat exchange part 12 includes plural tubes 12 a and plural fins 12 b alternately stacked with each other in the horizontal direction. In FIG. 2, illustration of the tube 12 a and the fin 12 b is omitted. The tube 12 a is arranged to extend in the vertical direction Y1, Y2, and has a flat shape in the cross-section. A passage for flowing refrigerant is formed in the tube 12 a. The fin 12 b is what is called a corrugated fin formed by bending a thin metal plate. The fin 12 b is arranged between the tubes 12 a adjacent to each other in the horizontal direction, and is joined to the external surface of the tube 12 a. As shown in FIG. 2, the windward side heat exchange part 12 is divided into a first windward side core part 121 and a second windward side core part 122 in the stacking direction of the tube 12 a and the fin 12 b. Moreover, as shown in FIG. 1, the windward side heat exchange part 12 has a side plate 12 c on the both ends in the stacking direction of the tube 12 a and the fin 12 b. The side plate 12 c is a component for reinforcing the windward side heat exchange part 12.

The windward side distribution tank 13 is a cylindrical component in which a passage for refrigerant is defined. The both ends of the windward side distribution tank 13 in the axial direction are closed. As shown in FIG. 2, the windward side distribution tank 13 has a partition board 13 a at the central part in the axial direction. The partition board 13 a divides the internal passage of the windward side distribution tank 13 into a first distribution part 131 and a second distribution part 132. Plural through holes, which are not illustrated, are defined in the external surface of the windward side distribution tank 13, and the lower end of the tube 12 a in the vertical direction Y1 is inserted into the through hole. The internal passage of the first distribution part 131 is communicated to the tube 12 a of the first windward side core part 121 by the through hole, and the internal passage of the second distribution part 132 is communicated to the tube 12 a of the second windward side core part 122 by the through hole. That is, the first distribution part 131 distributes refrigerant to the tubes 12 a of the first windward side core part 121. Moreover, the second distribution part 132 distributes refrigerant to the tubes 12 a of the second windward side core part 122.

As shown in FIG. 3, a joint portion 133 having a plane shape is formed on the external surface of the windward side distribution tank 13 to extend in the axial direction. The joint portion 133 is a portion to which the switch tank 30 is joined. The joint portion 133 has a through hole 134 passing through to the internal passage of the first distribution part 131. The through hole 134 is a passage for leading the refrigerant from the switch tank 30 to the first distribution part 131. Moreover, the joint portion 133 has a through hole 135 passing through to the internal passage of the second distribution part 132. The through hole 135 is a passage for leading the refrigerant from the switch tank 30 to the second distribution part 132.

As shown in FIG. 1 and FIG. 2, the windward side collection tank 11 is a cylindrical component in which a passage is defined for refrigerant. One end part of the windward side collection tank 11 in the axial direction is closed. The other end part of the windward side collection tank 11 in the axial direction defines a refrigerant outlet 11 a. The refrigerant outlet 11 a is connected to the intake side of the non-illustrated compressor. Moreover, non-illustrated plural through holes are formed in the external surface of the windward side collection tank 11, and the upper end of the tube 12 a in the vertical direction Y2 is inserted into the through hole. The internal passage of the windward side collection tank 11 is communicated to the tube 12 a of the first windward side core part 121 and the tube 12 a of the second windward side core part 122 by the respective through holes. That is, the refrigerant which flows through the tube 12 a of the first windward side core part 121, and the refrigerant which flows through the tube 12 a of the second windward side core part 122 are brought together into the windward side collection tank 11. The refrigerant collected in the windward side collection tank 11 is introduced into the compressor through the refrigerant outlet 11 a.

The leeward side evaporation part 20 has a leeward side distribution tank 21, a leeward side heat exchange part 22, and a leeward side collection tank 23. The leeward side distribution tank 21, the leeward side heat exchange part 22, and the leeward side collection tank 23 are arranged in this order downward in the vertical direction Y1.

The leeward side heat exchange part 22 has the structure approximately the same as the windward side heat exchange part 12. That is, the leeward side heat exchange part 22 has a rectangular parallelepiped shape, and is arranged so that the air flowing direction X corresponds to the thickness direction. The leeward side heat exchange part 22 includes plural tubes 22 a and plural fins 22 b alternately stacked with each other in the horizontal direction, and has a side plate 22 c on the both ends in the stacking direction of the tube 22 a and the fin 22 b. The leeward side collection tank 23 is attached to a lower end surface 22 d of the leeward side heat exchange part 22 in the vertical direction Y1. The leeward side distribution tank 21 is attached to an upper end surface 22 e of the leeward side heat exchange part 22 in the vertical direction Y2. Moreover, as shown in FIG. 2, the leeward side heat exchange part 22 is divided into a first leeward side core part 221 opposing the first windward side core part 121 and a second leeward side core part 222 opposing the second windward side core part 122 in the air flowing direction X.

The leeward side distribution tank 21 is a cylindrical component which has a passage for refrigerant inside. One end part of the leeward side distribution tank 21 in the axial direction is closed. The other end part of the leeward side distribution tank 21 in the axial direction defines a refrigerant inlet 21 a. Low-pressure refrigerant decompressed by the non-illustrated expansion valve flows into the refrigerant inlet 21 a. Moreover, non-illustrated plural through holes are formed in the external surface of the leeward side distribution tank 21, and the upper end of the tube 22 a in the vertical direction Y2 is inserted into the through hole. The internal passage of the leeward side distribution tank 21 is communicated to the tube 22 a of the first leeward side core part 221 and the tube 22 a of the second leeward side core part 222 by the through hole. That is, the refrigerant which flowed into the leeward side distribution tank 21 from the refrigerant inlet 21 a is distributed to the tube 22 a of the first leeward side core part 221 and the tube 22 a of the second leeward side core part 222.

The leeward side collection tank 23 is a cylindrical component which has a passage for refrigerant inside. The both ends of the leeward side collection tank 23 in the axial direction are closed. The leeward side collection tank 23 has a partition board 23 a at the central part in the axial direction. As shown in FIG. 2, the partition board 23 a divides the internal passage of the leeward side collection tank 23 into a first collection part 231 and a second collection part 232. Moreover, non-illustrated plural through holes are formed in the external surface of the leeward side collection tank 23, and the lower end of the tube 22 a in the vertical direction Y1 is inserted into the through hole. Due to the through hole, the internal passage of the first collection part 231 is communicated to the tube 22 a of the first leeward side core part 221, and the internal passage of the second collection part 232 is communicated to the tube 22 a of the second leeward side core part 222. That is, the refrigerant which flows through the tubes 22 a of the first leeward side core part 221 is brought together in the first collection part 231. Moreover, the refrigerant which flows through the tubes 22 a of the second leeward side core part 222 is brought together in the second collection part 232.

As shown in FIG. 3, the external surface of the leeward side collection tank 23 defines a joint portion 233 having a plane shape to extend in the axial direction. The joint portion 233 is a portion to which the switch tank 30 is joined. The joint portion 233 has a through hole 234 passing through to the internal passage of the first collection part 231. The through hole 234 is a passage for introducing the refrigerant from the first collection part 231 to the switch tank 30. Moreover, the joint portion 233 has a through hole 235 passing through to the internal passage of the second collection part 232. The through hole 235 is a passage for introducing the refrigerant from the second collection part 232 to the switch tank 30.

In this embodiment, the leeward side collection tank 23 corresponds to a first tank, and the windward side heat exchange part 12 corresponds to a second tank. Moreover, the leeward side heat exchange part 22 corresponds to a first heat exchange part, and the windward side heat exchange part 12 corresponds to a second heat exchange part.

The switch tank 30 is arranged between the windward side distribution tank 13 and the leeward side collection tank 23. In this embodiment, the switch tank 30 corresponds to a third tank. The switch tank 30 is a cylindrical component which has a passage for refrigerant inside. A partition component 301 is disposed inside the switch tank 30. The partition component 301 divides the interior space of the switch tank 30 to a first refrigerant passage 302 and a second refrigerant passage 303.

As shown in FIG. 3, the external surface of the switch tank 30 defines a joint portion 304 having a plane shape to which the joint portion 133 of the windward side distribution tank 13 is joined, and a joint portion 305 having a plane shape to which the joint portion 233 of the leeward side collection tank 23 is joined.

A through hole 306 passing through to the first refrigerant passage 302 is formed in the joint portion 304. The through hole 306 is located to be connected with the through hole 134 of the windward side distribution tank 13. A through hole 307 passing through to the first refrigerant passage 302 is formed in the joint portion 305. The through hole 307 is located to be connected with the through hole 235 of the leeward side collection tank 23. That is, the refrigerant brought together in the second collection part 232 of the leeward side collection tank 23 flows into the first refrigerant passage 302 through the through hole 235 of the leeward side collection tank 23 and the through hole 307 of the switch tank 30. The refrigerant which flowed into the first refrigerant passage 302 is led to the first distribution part 131 of the windward side distribution tank 13 through the through hole 306 of the switch tank 30 and the through hole 134 of the windward side distribution tank 13.

A through hole 308 passing through to the second refrigerant passage 303 is formed in the joint portion 304. The through hole 308 is located to be connected with the through hole 135 of the windward side distribution tank 13. A through hole 309 passing through to the second refrigerant passage 303 is formed in the joint portion 305. The through hole 309 is located to be connected with the through hole 234 of the leeward side collection tank 23. That is, the refrigerant brought together in the first collection part 231 of the leeward side collection tank 23 flows into the second refrigerant passage 303 through the through hole 234 of the leeward side collection tank 23 and the through hole 309 of the switch tank 30. The refrigerant which flowed into the second refrigerant passage 303 is led to the second distribution part 132 of the windward side distribution tank 13 through the through hole 308 of the switch tank 30 and the through hole 135 of the windward side distribution tank 13.

Thus, the switch tank 30 functions as a portion which introduces the refrigerant collected in the leeward side collection tank 23 to the windward side distribution tank 13. Moreover, the switch tank 30 functions as a portion which exchanges the flows of refrigerant in the leeward side heat exchange part 22 and the flows of refrigerant in the windward side heat exchange part 12 with each other in the stacking direction of the tubes 12 a, 22 a.

Next, the flow of refrigerant in the refrigerant evaporator 1 and a method of cooling air are explained.

The refrigerant decompressed by the non-illustrated expansion valve is introduced into the leeward side distribution tank 21 from the refrigerant inlet 21 a, as shown in an arrow A in FIG. 4. The refrigerant is distributed in the leeward side distribution tank 21, as shown by arrows B and C, to flow into the first leeward side core part 221 and the second leeward side core part 222 of the leeward side distribution tank 21.

The refrigerant which flowed into the first leeward side core part 221 and the second leeward side core part 222 flows through inside of each tube 22 a downward in the vertical direction Y1. At this time, the refrigerant which flows through the inside of the tube 22 a performs heat exchange with air flowing outside of the tube 22 a in the air flowing direction X. Thereby, a part of the refrigerant is evaporated to absorb heat from air, such that the air is cooled.

The refrigerant which flows through the tubes 22 a of the first leeward side core part 221 is brought together in the first collection part 231 of the leeward side collection tank 23, as shown in an arrow D. The refrigerant brought together in the first collection part 231 flows into the second distribution part 132 of the windward side distribution tank 13 through the second refrigerant passage 303 of the switch tank 30, as shown in an arrow F. The refrigerant which flowed into the second distribution part 132 flows into the second windward side core part 122, as shown in an arrow H.

The refrigerant which flows through the tubes 22 a of the second leeward side core part 222 is brought together in the second collection part 232 of the leeward side collection tank 23, as shown in an arrow E. The refrigerant brought together in the second collection part 232 flows into the first distribution part 131 of the windward side distribution tank 13 through the first refrigerant passage 302 of the switch tank 30, as shown in an arrow G. The refrigerant which flowed into the first distribution part 131 flows into the first windward side core part 121, as shown in an arrow I.

The refrigerant which flowed into the first windward side core part 121 and the second windward side core part 122 flows through the inside of the respective tube 22 a upward in the vertical direction Y2. At this time, the refrigerant which flows through the inside of the tube 22 a performs heat exchange with air which flows outside of the tube 22 a in the air flowing direction X. Thereby, a part of the refrigerant is evaporated to absorb heat from air, such that the air is cooled.

The refrigerant which flows through the first windward side core part 121 and the second windward side core part 122 is brought together in the windward side collection tank 11, as shown in arrows K and J. The refrigerant brought together in the windward side collection tank 11 is supplied to the intake side of the non-illustrated compressor from the refrigerant outlet 11 a of the windward side collection tank 11, as shown in an arrow L.

If water is condensed on the external surfaces of the windward side heat exchange part 12 and the leeward side heat exchange part 22 due to the heat exchange between refrigerant and air, the condensed water flows downward in the vertical direction Y1. As shown in FIG. 5, the condensed water may stay in a clearance CL1 among the windward side distribution tank 13, the leeward side collection tank 23, and the switch tank 30. If the condensed water staying in the clearance CL1 is frozen by a temperature fall, each of the tanks 13, 23, and 30 may be damaged, because the volume of water is increased, as what is called a freeze crack.

According to the present embodiment, the refrigerant evaporator 1 has a drainage structure for discharging the condensed water staying in the clearance CL1. Next, the details of the drainage structure are explained.

As shown in FIG. 3, plural drain grooves 310 are formed in the joint portion 304 of the switch tank 30 along the slope surface of the joint portion 304. Moreover, a drain groove 136 is formed in the joint portion 133 of the windward side distribution tank 13 at the position corresponding to the drain groove 310 of the joint portion 304 of the switch tank 30. As shown in FIG. 5, a straight-shaped drainage passage 40 is defined by a space surrounded by the drain groove 310 formed in the joint portion 304 of the switch tank 30 and the drain groove 136 formed in the joint portion 133 of the windward side distribution tank 13. One end part of the drainage passage 40 defines an inflow port 41 communicated to the clearance CL1. The other end part of the drainage passage 40 defines an outlet port 42 open to the lower space of the windward side distribution tank 13 in the vertical direction Y1. The outlet port 42 is located on the lower side of the clearance CL1 in the vertical direction Y1.

As shown in FIG. 3, plural drain grooves 311 are formed in the joint portion 305 of the switch tank 30 along the slope surface of the joint portion 305. Moreover, a drain groove 236 is formed in the joint portion 233 of the leeward side collection tank 23 at the position corresponding to the drain groove 311 of the joint portion 305 of the switch tank 30. As shown in FIG. 5, a straight-shaped drainage passage 50 is defined by a space surrounded by the drain groove 311 formed in the joint portion 305 of the switch tank 30 and the drain groove 236 formed in the joint portion 233 of the leeward side collection tank 23. One end part of the drainage passage 50 defines an inflow port 51 communicated to the clearance CL1. The other end part of the drainage passage 50 defines an outlet port 52 open to the lower space of the leeward side collection tank 23 in the vertical direction Y1. The outlet port 52 is located on the lower side of the clearance CL1 in the vertical direction Y1.

In FIG. 2 and FIG. 4, each illustration of the drain groove 310, 311 of the switch tank 30, the drain groove 136 of the windward side distribution tank 13, and the drain groove 236 of the leeward side collection tank 23 is omitted.

According to the refrigerant evaporator 1 of this embodiment explained above, the operation and advantage described in following (1) and (2) can be acquired.

(1) As shown in arrows W1 and W2 in FIG. 5, the condensed water can be discharged from the clearance CL1 outside through the drainage passage 40 or/and the drainage passage 50. Therefore, a freeze crack resulting from the freeze of condensed water can be restricted since it is difficult for the condensed water to stay in the clearance CL1.

(2) The outlet port 42 of the drainage passage 40 and the outlet port 52 of the drainage passage 50 are positioned on the lower side of the clearance CL1 in the vertical direction Y1. Since the condensed water trapped by the clearance CL1 becomes easy to be discharged, a freeze crack can be more certainly restricted.

(First Modification)

Next, a first modification of the refrigerant evaporator 1 of the first embodiment is explained.

As shown in FIG. 6, in the refrigerant evaporator 1 of this modification, the cross-section area of the outlet port 42 of the drainage passage 40 is larger than the cross-section area of the inflow port 41 of the drainage passage 40. Similarly, the cross-section area of the outlet port 52 of the drainage passage 50 is larger than the cross-section area of the inflow port 51 of the drainage passage 50. Since the condensed water trapped by the clearance CL1 becomes easier to be discharged according to such a structure, a freeze crack can be controlled effectively. The same action and effect can be acquired when the cross-section area of the outlet port 42 is more than or equal to the cross-section area of the inflow port 41. The same action and effect can be acquired when the cross-section area of the outlet port 52 is more than or equal to the cross-section area of the inflow port 51. [0047]

(Second Modification)

Next, a second modification of the refrigerant evaporator 1 of the first embodiment is explained.

As shown in FIG. 7, the drainage passage 40, 50 may be defined of only the drain groove 310, 311 formed in the switch tank 30. Moreover, as shown in FIG. 8, the drainage passage 40 may be defined of only the drain groove 136 formed in the windward side distribution tank 13. Furthermore, the drainage passage 50 may be defined of only the drain groove 236 formed in the leeward side collection tank 23. In short, the drainage passage for discharging the water trapped by the clearance CL1 is defined by at least one of the joint portion 133, 304 between the windward side distribution tank 13 and the switch tank 30, and the joint portion 233, 305 between the leeward side collection tank 23 and the switch tank 30 shown in FIG. 2.

(Third Modification)

Next, a third modification of the refrigerant evaporator 1 of the first embodiment is explained.

As shown in FIG. 9, the drainage passage 40, 50 may have a curved shape. In addition, the form of the drainage passage 40, 50 can be suitably changed, without being limited to the form shown in FIG. 5 to FIG. 9.

(Fourth Modification)

Next, a fourth modification of the refrigerant evaporator 1 of the first embodiment is explained.

As shown in FIG. 10, in the refrigerant evaporator 1 of this modification, the cross-section area of the narrowest clearance between the windward side distribution tank 13 and the windward side collection tank 23 is set as “Sa.” Moreover, the cross-section area of the inflow port 41 of the drainage passage 40 is set as “Sb1”, and the cross-section area of the outlet port 42 of the drainage passage 40 is set as “Sc1.” Furthermore, the cross-section area of the inflow port 51 of the drainage passage 50 is set as “Sb2”, and the cross-section area of the outlet port 52 of the drainage passage 50 is set as “Sc2.”

These cross-section areas Sa, Sb1, Sb2, Sc1, and Sc2 are set to satisfy the following relation formulas f1 and f2.

Sa<Sb1≦Sc1   (f1)

Sa<Sb2≦Sc2   (f2)

Accordingly, since the condensed water which flows into the clearance CL1 from the narrowest portion between the windward side distribution tank 13 and the windward side collection tank 23 can be easily drained, a freeze crack can be controlled effectively.

In addition, in case where the refrigerant evaporator 1 is arranged with the slanting posture, if the drainage passage, among the drainage passage 40 and the drainage passage 50, arranged on the lower side in the vertical direction satisfies the formulas, the same operation and advantage can be acquired. The slanting posture represents an orientation in which the longitudinal direction of the tubes 12 a and 22 a intersects the vertical direction.

Second Embodiment

Next, a second embodiment of the refrigerant evaporator 1 is described hereafter focusing on differences from the first embodiment.

As shown in FIG. 11, the windward side distribution tank 13 and the leeward side collection tank 23 of this embodiment are formed integrally with each other. Specifically, the windward side distribution tank 13 and the leeward side collection tank 23 are configured to have a core plate 61 and a tank portion 62.

The tube 12 a of the windward side heat exchange part 12 and the tube 22 a of the leeward side heat exchange part 22 are inserted and joined to the core plate 61. The core plate 61 is formed to have approximately W-shaped cross-section. In detail, the core plate 61 has a windward side tube bonded surface 611 and a leeward side tube bonded surface 612. The tube 12 a of the windward side heat exchange part 12 is inserted and joined to the windward side tube bonded surface 611. The tube 22 a of the leeward side heat exchange part 22 is inserted and joined to the leeward side tube bonded surface 612. The core plate 61 has a core plate side projection part 613 arranged between the two tube bonded surfaces 611, 612. The core plate side projection part 613 is projected away from the heat exchange part 12, 22 relative to the two tube bonded surfaces 611, 612. The core plate side projection part 613 has plural openings 613 a arranged in the longitudinal direction, that is a direction perpendicular to both of the air flowing direction X and the vertical direction Y1, Y2.

The tank portion 62 defines a tank space with the core plate 61. The tank space represents the first distribution part 131 and the second distribution part 132 of the windward side distribution tank 31, and the first collection part 231 and the second collection part 232 of the leeward side collection tank 23, shown in FIG. 2. The tank portion 62 is formed to have approximately W-shaped cross-section. In detail, the tank portion 62 has a windward side tank the portion 621 and a leeward side tank portion 622. The windward side tank portion 621 defines the first distribution part 131 and the second distribution part 132 with the windward side tube bonded surface 611. The leeward side tank portion 622 defines the first collection part 231 and the second collection part 232 with the leeward side tube bonded surface 612. The tank portion 62 has a tank portion side projection part 623 arranged between the two tank portions 621 and 622. The tank portion side projection part 623 is projected toward the windward side heat exchange part 12 and the leeward side heat exchange part 22 relative to the two tank portions 621, 622. The tank portion side projection part 623 has plural openings 623 a arranged in the longitudinal direction, that is, a direction perpendicular to both of the air flowing direction X and the vertical direction Y1, Y2.

The core plate side projection part 613 of the core plate 61 and the tank portion side projection part 623 of the tank portion 62 are joined to each other. The space formed of the core plate 61 and the tank portion 62 is divided into the windward side distribution tank 13 and the leeward side collection tank 23. In other words, the core plate side projection part 613 and the tank portion side projection part 623 operate as a connection part 70 which connects the windward side distribution tank 13 and the leeward side collection tank 23 to each other.

The opening 613 a and the opening 623 a are arranged at least partially overlap with each other. Thereby, the opening 613 a and the opening 623 a function as a drainage hole to drain water condensed, due to heat exchange between refrigerant and air, on the external surfaces of the windward side heat exchange part 12 and the leeward side heat exchange part 22.

A space CL2 is defined between the upper part of the switch tank 30 and the tank portion 62. The space CL2 is communicated to a space where the windward side heat exchange part 12 and the leeward side heat exchange part 22 are arranged through the opening 613 a and the opening 623 a. The space CL2 is located below the opening 613 a and the opening 623 a in the vertical direction Y1.

The external surface of the tank portion 62 located on the outer side when attached to the core plate 61 has the joint portion 621 a and the joint portion 622 a. The joint portion 621 a is a portion joined to the joint portion 304 of the switch tank 30. The joint portion 622 a is a portion joined to the joint portion 305 of the switch tank 30.

The drain groove 621 b is formed on the joint portion 621 a at the position corresponding to the drain groove 310 of the joint portion 304 of the switch tank 30. The straight-shaped drainage passage 40 is defined by the space surrounded by the drain groove 310 formed in the joint portion 304 of the switch tank 30, and the drain groove 621 b. The drainage passage 40 is formed on the lower side of the opening 613 a, 623 a of the connection part 70. The inflow port 41 communicated to the space CL2 is formed at the end part of the drainage passage 40. The outlet port 42 open to the lower space of the windward side distribution tank 13 in the vertical direction Y1 is formed at the other end part of the drainage passage 40. The outlet port 42 is arranged on the lower side of the space CL2 in the vertical direction Y1. The space where the windward side heat exchange part 12 and the leeward side heat exchange part 22 are arranged is communicated to the drainage passage 40 through the opening 613 a, the opening 623 a, and the space CL2.

The drain groove 622 b is formed in the joint portion 622 a at the position corresponding to the drain groove 311 of the joint portion 305 of the switch tank 30. The straight-shaped drainage passage 50 is defined by the space surrounded by the drain groove 311 formed in the joint portion 305 of the switch tank 30, and the drain groove 622 b. The drainage passage 50 is formed on the lower side of the opening 613 a, 623 a of the connection part 70. The inflow port 51 communicated to the space CL2 is formed at the end part of the drainage passage 50. The outlet port 52 open to the lower space of the leeward side collection tank 23 in the vertical direction Y1 is formed at the other end part of the drainage passage 50. The outlet port 52 is arranged on the lower side of the space CL2 in the vertical direction Y1. The space where the windward side heat exchange part 12 and the leeward side heat exchange part 22 are arranged is communicated to the drainage passage 50 through the opening 613 a, the opening 623 a, and the space CL2.

A cross-section area of at least one of the inflow port 41 of the drainage passage 40 and the inflow port 51 of the drainage passage 50 is larger than each opening area of the opening 613 a and the opening 623 a. Thereby, the condensed water which flows into the space CL2 from the opening 613 a and the opening 623 a can be easily drained. Moreover, considering the viewpoint of the drainage property of condensed water, it is desirable to set the cross-section area of the outlet port 42 of the drainage passage 40 to be larger than the cross-section area of the inflow port 41 of the drainage passage 40. Similarly, it is desirable to set the cross-section area of the outlet port 52 of the drainage passage 50 to be larger than the cross-section area of the inflow port 51 of the drainage passage 50.

In addition, although illustration is omitted, similarly to the first embodiment, the joint portion 621 a has a through hole used as a passage for introducing the refrigerant from the switch tank 30 to the first distribution part 131, and a through hole used as a passage for introducing the refrigerant from the switch tank 30 to the second distribution part 132. Similarly, although illustration is omitted, the joint portion 622 a has a through hole used as a passage for introducing the refrigerant from the first collection part 231 to the switch tank 30, and a through hole used as a passage for introducing the refrigerant from the second collection part 232 to the switch tank 30.

According to the refrigerant evaporator 1 of this embodiment explained above, operation and advantage described in following (3) and (4) can be acquired.

(3) According to the refrigerant evaporator 1 of this embodiment, when water condensed, due to heat exchange between refrigerant and air, on the external surfaces of the windward side heat exchange part 12 and the leeward side heat exchange part 22, the condensed water flows downward in the vertical direction Y1, and passes through the opening 613 a and the opening 623 a. The condensed water which passed through the opening 613 a and the opening 623 a flows into the space CL2, and is discharged outside through the drainage passage 40 and the drainage passage 50. Thereby, a freeze crack can be more certainly restricted.

(4) A cross-section area of at least one of the inflow port 41 of the drainage passage 40 and the inflow port 51 of the drainage passage 50 is larger than each opening area of the opening 613 a and the opening 623 a. Thus, the condensed water can be easily discharged.

Other Embodiment

The refrigerant evaporator 1 of each embodiment may have only either one of the drainage passage 40 and the drainage passage 50.

The fluid to be cooled in the refrigerant evaporator 1 is not limited to air, and appropriate fluid can be used.

It should be appreciated that the present disclosure is not limited to the embodiments described above and can be modified appropriately within the scope of the present disclosure. The scope of the present disclosure is not limited to the range exemplified with the structure of the embodiment. The range of the present disclosure is shown by the appended claims, and also includes all the changes in the equivalence. For example, each element, its arrangement, material, condition, shape, size and the like in each embodiment is not limited to the example, and is suitably modified. It is possible to combine the elements of the embodiments, provided it is technically possible. 

What is claimed is:
 1. A refrigerant evaporator in which heat is exchanged between a fluid to be cooled and a refrigerant, the refrigerant evaporator comprising: a first heat exchange part in which the refrigerant flows to exchange heat between the fluid to be cooled and the refrigerant; a second heat exchange part in which the refrigerant flows to exchange heat between the fluid to be cooled and the refrigerant, the second heat exchange part being arranged to oppose the first heat exchange part; a first tank arranged below the first heat exchange part to distribute the refrigerant to the first heat exchange part; a second tank arranged below the second heat exchange part to collect the refrigerant flowing through the second heat exchange part; and a third tank joined to the first tank and the second tank to introduce the refrigerant collected by the second tank to the first tank, wherein a clearance is defined among the first tank, the second tank, and the third tank, and each of a joint portion between the first tank and the third tank and a joint portion between the second tank and the third tank defines a drainage passage to discharge water trapped in the clearance.
 2. The refrigerant evaporator according to claim 1, wherein the drainage passage has an outlet port located below the clearance.
 3. The refrigerant evaporator according to claim 1, wherein the drainage passage is an arc-shaped water passage.
 4. The refrigerant evaporator according to claim 1, wherein the drainage passage is a straight-shaped water passage.
 5. The refrigerant evaporator according to claim 1, wherein a cross-section area of an outlet port of the drainage passage is more than or equal to a cross-section area of an inflow port of the drainage passage.
 6. The refrigerant evaporator according to claim 1, wherein a cross-section area of an inflow port of the drainage passage is larger than a cross-section area of a narrowest clearance between the first tank and the second tank.
 7. A refrigerant evaporator in which heat is exchanged between a fluid to be cooled and a refrigerant, the refrigerant evaporator comprising: a first heat exchange part in which the refrigerant flows to exchange heat between the fluid to be cooled and the refrigerant; a second heat exchange part in which the refrigerant flows to exchange heat between the fluid to be cooled and the refrigerant, the second heat exchange part being arranged to oppose the first heat exchange part; a first tank arranged below the first heat exchange part to distribute the refrigerant to the first heat exchange part; a second tank arranged below the second heat exchange part to collect the refrigerant flowing through the second heat exchange part; a connection part that connects the first tank and the second tank to each other; and a third tank joined to the first tank and the second tank to introduce the refrigerant collected by the second tank to the first tank, wherein at least one opening is defined in the connection part, and each of a joint portion between the first tank and the third tank and a joint portion between the second tank and the third tank defines a drainage passage located below the opening of the connection part to discharge water passing through the opening.
 8. The refrigerant evaporator according to claim 7, wherein a cross-section area of an inflow port of the drainage passage is larger than an opening area of the opening.
 9. The refrigerant evaporator according to claim 1, wherein the drainage passage defined in the joint portion between the first tank and the third tank has an inflow port communicated with the clearance, and the drainage passage defined in the joint portion between the second tank and the third tank has an inflow port communicated with the clearance.
 10. The refrigerant evaporator according to claim 7, wherein the drainage passage defined in the joint portion between the first tank and the third tank has an inflow port communicated with a lower space of the opening, and the drainage passage defined in the joint portion between the second tank and the third tank has an inflow port communicated with the lower space of the opening. 